"True Blood" star Stephen Moyer had a frightening moment on the race track at the Long Beach Grand Prix earlier today -- when he flipped his car during a qualifying lap ... but was able to walk away.


We're told the car flipped once ... and landed on its wheels. Moyer didn't appear to be injured and got out of the car on his own.

Moyer even gave a thumbs up to the crowd.

TMZ obtained footage showing Moyer emerging from his vehicle moments after the incident.

UPDATE: A rep for the race tells us, "The actor emerged unscathed -- and the top celebrity qualifier based on individual lap time."